The present invention relates to a tube bending machine with a bending table tiltable about an axis and which includes a bending template, clamping means movable toward and away from the bending template and an advancing carriage including a releasable clamping collet, which during the bending operation is movable toward the bending template.
During bending of tubes it is usually desired to make successive bends in the tube with the same bending radius to avoid during the bending of the tube a change of the bending templates. However, in many applications it is necessary to make successive bends with a different bending radius. For instance, during the bending of exhaust tubes for motor vehicles it is desirable to calculate the bending radius of the tube in order to obtain with the exhaust tube a predetermined pressure. This predetermined bending radius can, however, not be used for subsequent bending of the tube.
Tube bending machines are known in the art which comprise two superimposed fixedly arranged bending templates of different diameters. In using these known tube bending machines, the tube to be bent is first manually applied to the first bending template and, after bending, manually applied to the second bending template. This procedure is not only rather cumbersome but leads also to unexact results.
In order to bend tubes with different bending radii, one proceeded so far by bending a plurality of tubes with a first bending radius, by removing then the tubes from the bending machine and storing the same in the region of the machine, whereafter the used bending template has been removed from the bending machine and a new bending template with a different diameter has been placed thereon, whereafter the bent tubes are again placed into the machine to be provided with a subsequent bend having a different bending radius. This procedure is likewise not only cumbersome and time consuming but leads also to difficulties with respect to the exactness of the distances and angular positions of the successive bends with different bending radii. If the tube after a first bend or a plurality of first bends with the same bending radius is taken out of the machine, then it is difficult to place the tube bent in two or three different planes again into the bending machine. This requires to place the tube manually into the machine. A further difficulty arises to maintain the original position at which the tube has been held by the advancing carriage and the clamping collet connected thereto during the renewed placement of the tube into the clamping collet so that in the finished bent tube the distances between the bends of different bending radii and the angular position of the subsequent bends with different bending radii could not exactly be maintained. These difficulties also required additional adjusting operations on the finished tubes. Such subsequent adjusting operations are, however, not economical during serial production of tubes in which a great number of bent tubes have to be produced per time unit. From the above, it will be clear that bending of tubes with a plurality of subsequent bends of different bending radii has not been possible up to now with fully automatic, especially numerically controlled tube bending machines.